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Biomedical subjects

L Dahlin

Publications and source records attributed to L Dahlin.

At least 19 recordsLinked to original sources
PubMed1998

Hyperbaric oxygen treatment enhances regeneration of the rat sciatic nerve.

The effect of hyperbaric oxygen (HBO) treatment on regeneration of the rat sciatic nerve was studied. The sciatic nerve was crushed with a pair of pliers and the animals were either left untreated or subjected to a series of 45-min exposures to 100% O2 at 3.3 atm absolute pressure at 0, 4, and 8 h postoperatively and then every 8 h. Regeneration was evaluated using the pinch-reflex test at 3, 4, or 5 days following surgery and with neurofilament staining at 4 days. The regeneration distances at all time points were significantly longer in animals exposed to hyperbaric oxygen treatment independent of the evaluation procedure. A short initial period of the same HBO treatment schedule, with no more treatments after 25 h, appeared as effective as when treatments were maintained being given every 8 h until evaluation. We conclude that HBO treatment stimulates axonal outgrowth following a nerve crush lesion.

Animals↗
PubMed1997

A new type of "bioartificial" nerve graft for bridging extended defects in nerves.

In the rat sciatic nerve, a gap of around 10 mm in nerve continuity seems to be the maximal distance which can be successfully repaired by silicone tubes. In this study we tested if a new artificial nerve graft, composed of eight polyamide filaments (diameter 250 microns) placed inside silicone tubes (1.8 mm inner diameter), could be used to bridge an extended gap (15 mm) in rat sciatic nerve. Silicone tubes containing eight polyamide sutures were found to support regeneration across such a gap. After 4 weeks sensory fibres had bridged the gap and grown into the distal nerve segment as revealed by a positive pinch reflex test as well as positive staining for neurofilaments in the distal nerve segment. Myelinated axons could be observed in the tissue matrix formed in between and peripheral to the synthetic filaments along the whole length of the tube. In contrast, when silicone tubes without filaments were used to bridge the 15 mm gap, the tubes contained only fluid or in two cases a thin tissue strand. No positive pinch reflex response was elicited in the nerve segment distal to such a tube. We conclude that the new artificial nerve graft can be used to support regeneration across extended gaps in nerves.

Animals↗
PubMed1997

Tubular versus conventional repair of median and ulnar nerves in the human forearm: early results from a prospective, randomized, clinical study.

Injury to a peripheral nerve is followed by local synthesis and release of neurotrophic factors of importance for the regeneration process. This concept was adopted for repair of transected human median and ulnar nerves in the forearm. As an alternative to conventional microsurgical repair of the nerve trunk, silicone tubes of appropriate size were used to enclose the injury zone, intentionally leaving a gap measuring 3-4 mm between the nerve ends inside the tube. The early results from a prospective, randomized, clinical study comparing this principle with conventional microsurgical technique for repair of human median and ulnar nerves, is presented. Eighteen patients (14 men and 4 women), aged 12-72 (mean, 29.5) years, were randomized to either tubulization (11 cases) or conventional microsurgical repair (7 cases). A battery of tests for sensory and motor functions of the hand were carried out at regular intervals for up to 1 year after surgery. The results show no difference between the both techniques, with the exception of perception of touch, which showed a significant difference (p < .05) at the 3-month checkup in favor of the tubulization technique. At re-exploration 11 months after the initial procedure (1 case), the former gap was replaced by regenerated nerve tissue in direct continuity with the proximal and distal parts of the nerve trunk, the exact level of the former injury being impossible to identify. Study data demonstrate an intrinsic capacity of human major nerve trunks to reconstruct themselves in a preformed space when an optimal environment is offered and the surgical trauma is minimized.

Adolescent↗
PubMed1996

Tubulization increases axonal outgrowth of rat sciatic nerve after crush injury.

It is important to develop methods which increase nerve regeneration since restoration of function following injury to peripheral nerves often requires outgrowth of the injured axons over long distances. In this study, axonal outgrowth after bilateral crush injury to the sciatic nerve of the rat was measured. One group with large-diameter nonpermeable silicone tubes and one group with large diameter permeable silicone tubes applied around the crush site on one side had regeneration following nerve injury compared to controls on the other side. The length of regeneration of the regenerating axons were then measured 4, 5, and 6 days following the crush injury using the "pinch reflex test." The presence of axons at the pinch level was confirmed by immunocytochemical staining for neuro-filaments. The length of regeneration for rats with nonpermeable tubes was significantly greater than that of the contralateral control side and was so at all times (p < 0.05). The effect was present but not that pronounced where permeable tubes were used. We conclude that the outgrowth of regenerating sensory axons after sciatic nerve crush injury in the rat can be increased by enclosing the regeneration site in a silicone tube. The observed effect may be due to local mechanisms such as macrophage invasion or prevention of rapid wash-out of fluid from the crush zone.

Animals↗
PubMed1995

Intelligence and temperament as protective factors for mental health. A cross-sectional and prospective epidemiological study.

The Sjöbring system of personality dimensions measuring intellectual capacity, activity, impulsivity and sociability was used to study possible "salutogenic" (i.e. causes of health) effects. The study comprised 590 subjects investigated in 1947, 1957, 1972 and 1988-1989 in the Lundby project, an epidemiological study in Sweden. Psychiatric diagnoses were made in 1947, 1957 and 1972. Mental health was estimated in 1988-1989 using the concept "love well, work well, play well and expect well". The Sjöbring dimensions were clinically assessed in 1972. Both in the concurrent study in 1972 and in the prospective study in 1988-1989 "super capacity" (high intellectual function), "super validity" (high activity level) and "super solidity" (low impulsivity) were statistically associated with lower frequencies of certain psychiatric diagnoses and a higher frequency of positive mental health. These variables are proposed to increase coping capacity, and therefore increase stress resilience.

Adolescent↗
PubMed1995

Long-term local corticosteroid application does not influence nerve transmission or structure.

The long-term effects of a locally applied depot form of a corticosteroid on the electrical properties and structure of nerves were investigated in an animal experimental model. The conduction in electrically stimulated A-fibres of the plantar nerve was monitored by a bipolar volley recording of the sciatic nerve whereas the conduction in C-fibres of the plantar nerve was measured through a C-fibre evoked segmental flexion reflex in the anaesthetized rat. Droplets of either methylprednisolone acetate or vehicle were placed under direct observation on the plantar nerve. Saline was used as a control on the contralateral side. One to two weeks after the application both the A-fibre volley of the sciatic nerve and the C-fibre evoked reflex discharge of flexor motoneurons were recorded. No difference was found between the nerves treated with corticosteroid, constituent vehicle or saline. Light and electron microscopic analysis of the nerves showed no changes in the nerve fibres or in the intraneural connective tissue in either the corticosteroid treated or the control nerves. It is concluded that locally applied corticosteroids in limited amounts have no long-term effects on the electrical and structural properties of peripheral nerves.

Administration, Topical↗
PubMed1995

Coping with life span crises in a group at risk of mental and behavioral disorders: from the Lundby study.

The subjects belong to a prospective, longitudinal population study on mental health, the Lundby study, performed in 1947, 1957 and 1972. In 1988-1989, 148 individuals, then 42-56 years of age, raised in families with at least 3 risk factors for mental or behavioral disorders, were interviewed about their life span coping style. Twenty-two coping mechanisms were rated; optimism, substitution, wishful thinking, problem-solving, planning, self-reliance, humor, acceptance, resignation, social support, comparison with others, religion, catharsis, self-criticism, value reinforcement, alcohol and drug consumption, professional help, endurance, information-seeking, isolating activity, magic and minimizing. Together they contributed statistically significantly to mental health (explained variance 24%) and quality of life (explained variance 28%). Problem-solving, social support and optimism were frequently used and were statistically associated with positive mental health and lower frequencies of some mental disorders. Sense of coherence, a personal disposition factor, was also statistically associated (explained variance 22%) with the combined coping mechanisms.

Data Collection↗
PubMed1994

Effects of electro-acupuncture and physical exercise on regional concentrations of neuropeptides in rat brain.

The effects of single or repeated treatments with manual acupuncture (ACU), electro-acupuncture (ELACU) or physical exercise on neuropeptide Y (NPY), neurokinin A (NKA), substance P (SP), galanin (GAL) and vasoactive intestinal peptide (VIP)-like immunoreactivity (-LI) in different regions of the rat brain were studied. Initially the effect of microwave irradiation (MWI) was compared to decapitation on the recovery of neuropeptides, and significantly higher concentrations of SP-LI, NKA-LI and NPY-LI were found in the hippocampus, occipital cortex, pituitary and striatum following MWI. Repeated ELACU treatments significantly increased SP-LI, NKA-LI and NPY-LI in the hippocampus and NPY-LI in the occipital cortex. No changes were found in animals receiving ACU or performing physical exercise.

Acupuncture Therapy↗
PubMed1994

Salutogenic childhood factors reported by middle-aged individuals. Follow-up of the children from the Lundby study grown up in families experiencing three or more childhood psychiatric risk factors.

This study is salutogenic (= causes of health), focusing on factors which corresponded to good mental health in subjects who had been exposed to at least three child psychiatric risk factors when growing up. The material was drawn from a prospective, longitudinal population study on mental health, the Lundby Study, which was performed in three waves in 1947, 1957 and 1972. In 1988/89, 148 individuals then 42-56 years of age, were re-visited and interviewed about their life span experiences. Factors previously found to increase stress resilience in children and adolescents were identified. The personal dispositions during childhood found to be associated with adult positive mental health were childhood positive self-esteem, successful coping, internal locus of control and intellectual capacity. Childhood family factors, such as trusting relations with a parent and shared values, were also important. Antonovsky's sense of coherence model can be used to explain the mechanisms by which the different variables can lead to health through increasing an individual's capacity for comprehensibility, manageability and meaningfulness, the three concepts of sense of coherence.

Adaptation, Psychological↗
PubMed1994

Tubular repair of the median nerve in the human forearm. Preliminary findings.

Transected median nerves in the forearm of two male patients, 12 and 21 years of age, were treated with a chamber technique leaving a 3 to 5 mm gap between the nerve ends. The nerve ends were enclosed in a silicone tube of such a dimension that would not cause compression of the nerve. Post-operative examination including sensory evaluation and assessment of muscle contraction force was carried out after 3 years. In both cases there was excellent motor recovery of the thenar muscles. Outgrowth of sensory fibres was remarkably fast, resulting ultimately in functional sensibility allowing almost normal hand function. 2PD was < or = 6 mm (12-year-old patient) and 8 to 10 mm (21-year-old patient) respectively. In one case the silicone tube was re-explored because of minor local discomfort 2 years after the repair. The former gap was bridged by a smooth continuous nerve-like structure of the same diameter as the adjacent nerve trunk and with no signs of neuroma formation or compression of the nerve.

Adult↗
PubMed1994

Trophism, tropism, and specificity in nerve regeneration.

Target-derived neurotrophic factors are of basic importance for survival of neurons. In the normal state, such neurotrophic factors, synthesized by the target tissues, are taken up by nerve terminals and transported by retrograde axonal transport in axons to the nerve-cell bodies to maintain their viability. After nerve injury, neurotrophic factors are synthesized by non-neuronal cells (Schwann cells and fibroblasts) in the nerve trunk, thereby supporting the outgrowth of axons. Neurite-outgrowth-promoting factors on cell surfaces (cell adhesion molecules, "recognition molecules") or in the extracellular matrix promote extension of the axons by providing an appropriate "adhesiveness" in the substrate. Both neurotrophic and neurite-outgrowth-promoting factors are essential for axonal growth after injury. Specificity in end-organ reinnervation is a complex phenomenon which may be based on physical factors at the zone of injury, as well as on molecular interaction between axons and substrate cells along the pathways and at the target level. Such processes may include molecular recognition of appropriate axons and maintenance of such axons by trophic mechanisms, as well as the pruning of inappropriate axons. The ultimate errors in target reinnervation are reflected in a cortical re-organization in the somatosensory cortex. The capacity of the brain to "reprogram" itself and adapt to this functional re-organization is critical for the ultimate recovery of functional sensory/motor function after nerve injuries.

Animals↗
PubMed1990

Childhood vulnerability and adult invincibility.

This study is salutogenic, focusing on the people who cope successfully with the handicapping background of a high-risk childhood. Of those aged 0-15 in 1947 in a total population survey of 2 Swedish parishes, 221 persons with 3 or more childhood psychiatric risk factors were identified. Personal interviews were conducted with 148 of them in 1988-1989. Four measures were used: the Sense of Coherence Scale, the Symptom Distress Checklist, the Quality of Life Scale, and a qualitative overall measure of health status using all interview material. Data analysis focuses on stressing the considerable proportion who managed to overcome their handicapped backgrounds. The sense of coherence is proposed as a powerful explanatory variable in such success.

Adaptation, Psychological↗